Q&A: What does a referendum on the European Union mean for Britain?

WHAT will David Cameron's historic speech mean for Britain?

David Cameron, Nick Clegg and Ed Miliband have all indicated they want Britain to remain in the EU

Are we definitely getting an in-or-out referendum on Britain's European Union membership?

Not quite. It depends on the outcome of the next election in 2015. David Cameron has committed the Tories to holding a referendum but that policy is not shared by Labour or Lib Dems. Even if the Tories are in a Coalition, they still may not have enough support to pass the legislation. And, under the Prime Minister's plan, the referendum is still five years away.

Why is the PM promising an in-or-out referendum?

Mr Cameron has bowed to intense pressure from the many Tory Euro-sceptics and from relentless campaigns such as the Daily Express's crusade for Britain to quit. Many Tories believe a referendum pledge is essential to stop the party losing millions of votes to Ukip.

David Cameron has bowed to intense pressure from the many Tory Euro-sceptics

What will the referendum question be?

That has yet to be decided. But Mr Cameron has indicated that voters will get a choice between accepting continued membership of the EU on new terms or leaving.

How will the parties divide during the referendum campaign?

Mr Cameron, Nick Clegg and Ed Miliband have all indicated they want Britain to remain in the EU and would back the campaign to stay in. But the main parties will be split and leaders will be under pressure to allow senior figures to adopt independent stances. Ukip will be united in campaigning for Britain to quit.

Is this Britain's first national referendum on Europe?

No. In 1975, the Labour government held a referendum on European Economic Community membership after Prime Minister Harold Wilson renegotiated terms. Just over 67 per cent of voters supported staying in.